Well, somebody asked the 'ultimate noob question' a few minutes earlier, so I supposed mine wasn't the ultimate but just almost.

And I guess when the answer is "um, it's part of the keyboard, you know, the d(irectional) pad you use for navigating," that's a clear sign that we are approaching ultimaticity.

And you know what? I'm not red-faced about not having figured this out at all. Instead, I'm really happy. Now I know. No more re-re-re-typing on the tiny-keyed keyboard in XTerm.